Breaking the carbon dimer: The challenges of multiple bond dissociation with full configuration interaction quantum Monte Carlo methods
Breaking the carbon dimer: The challenges of multiple bond dissociation with full configuration interaction quantum Monte Carlo methods
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DOI：
10.1063/1.3624383
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发表时间：
2011-08-28
影响因子：
4.4
通讯作者：
Alavi, Ali
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文献类型：
--
作者：
Booth, George H.;Cleland, Deidre;Alavi, Ali
全组态相互作用量子蒙特卡罗（FCIQMC）方法，以及它的“引发剂”的扩展（i-FCIQMC），是用来解决复杂的电子结构的碳二聚体在整个解离反应坐标，作为一个典型的例子，一个强相关的分子系统。使用各种基组的大小增加到大的cc-pVQZ，跨越一个完全可访问的N-电子的基础上超过10（12）斯莱特决定因素，并在每个基组的方法的准确性证明。收敛到FCI极限是在最大的基础上实现的，只有O[10（7）]步行者在整个结合曲线的零点几毫哈特树的随机误差条内，并在可能的情况下与FCI，CCSD（T），MRCI和CEEIS结果进行了广泛的比较。详细阐述了FCIQMC方法的收敛性，考虑了虚时间、步数和基的大小对收敛性的影响。各种对称性，可以纳入随机动态，超出标准的阿贝尔点群对称性和自旋极化也进行了描述。这些可以对计算的计算工作量以及收敛到各种激发态的能力具有显著的益处。所提出的结果表明，这种规模的系统的基础集能量的新的基准精度，显着提高了以前的最先进的估计。(C)2011年美国物理学会。[doi：10.1063/1.3624383]
The full configuration interaction quantum Monte Carlo (FCIQMC) method, as well as its "initiator" extension (i-FCIQMC), is used to tackle the complex electronic structure of the carbon dimer across the entire dissociation reaction coordinate, as a prototypical example of a strongly correlated molecular system. Various basis sets of increasing size up to the large cc-pVQZ are used, spanning a fully accessible N-electron basis of over 10(12) Slater determinants, and the accuracy of the method is demonstrated in each basis set. Convergence to the FCI limit is achieved in the largest basis with only O[10(7)] walkers within random errorbars of a few tenths of a millihartree across the binding curve, and extensive comparisons to FCI, CCSD(T), MRCI, and CEEIS results are made where possible. A detailed exposition of the convergence properties of the FCIQMC methods is provided, considering convergence with elapsed imaginary time, number of walkers and size of the basis. Various symmetries which can be incorporated into the stochastic dynamic, beyond the standard abelian point group symmetry and spin polarisation are also described. These can have significant benefit to the computational effort of the calculations, as well as the ability to converge to various excited states. The results presented demonstrate a new benchmark accuracy in basis-set energies for systems of this size, significantly improving on previous state of the art estimates. (C) 2011 American Institute of Physics. [doi:10.1063/1.3624383]